1. Field of the Invention
The present invention relates to a method of fabricating a single crystal gallium nitride substrate, a gallium nitride substrate and a nitride semiconductor epitaxial substrate.
2. Related Background Art
Publication 1 (Japanese Patent Application Laid Open No. 2001-196632) discloses a nitride based compound semiconductor light emitting device. This nitride based compound semiconductor light emitting device has an active layer and an acceptor-doped layer of nitride-based compound semiconductor on the surface of a GaN substrate, and the surface of crystal orientation is inclined in the range of 0.05 degrees to 2 degrees with reference to <0001> direction.
Publication 2 (Japanese Patent Application Laid Open No. 2000-223743) discloses a nitride based semiconductor light emitting device. This nitride based semiconductor light emitting device has a light generating layer of nitride-based semiconductor on the surface of a GaN substrate. In the nitride based semiconductor light emitting device, the surface of crystal orientation is inclined in the range of 0.03 degrees to 10 degrees.
Publication 3 (Japanese Patent Application Laid Open No. 2000-22212) discloses a GaN wafer. This GaN wafer is formed by polishing. The off-angle of the surface of the GaN wafer is within 3 degrees, the variation of the off-angle is within 4 degrees over the surface. The warpage of the GaN wafer is within 200 micrometers.